INFO: task kworker/u4:4:3920 blocked for more than 140 seconds.
Not tainted 4.9.111-g03c70fe #6
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:4 D28568 3920 2 0x00000000
Workqueue: events_unbound flush_to_ldisc
ffff8801d6069800 ffff8801bf577480 ffff8801bf577480 ffff8801d8589800
ffff8801db221c18 ffff8801d604f6c8 ffffffff839e7ded ffffffff81235607
0000000000000000 ffff8801d606a0c0 0000000600000007 ffff8801db2224e8
Call Trace:
[<ffffffff839e93ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
[<ffffffff839f4a28>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
[<ffffffff839f4a28>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
[<ffffffff81ee6a07>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
[<ffffffff839f27fc>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
[<ffffffff839f27fc>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
[<ffffffff8211c6fd>] isig+0xbd/0x4c0 drivers/tty/n_tty.c:1100
[<ffffffff8211d1a2>] n_tty_receive_signal_char+0x22/0xf0 drivers/tty/n_tty.c:1212
[<ffffffff821213d1>] n_tty_receive_char_special+0x10e1/0x2860 drivers/tty/n_tty.c:1258
[<ffffffff82124a9a>] n_tty_receive_buf_fast drivers/tty/n_tty.c:1579 [inline]
[<ffffffff82124a9a>] __receive_buf drivers/tty/n_tty.c:1613 [inline]
[<ffffffff82124a9a>] n_tty_receive_buf_common+0x18ea/0x2300 drivers/tty/n_tty.c:1711
[<ffffffff821254e3>] n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1746
[<ffffffff8212afdf>] tty_ldisc_receive_buf+0xaf/0x190 drivers/tty/tty_buffer.c:455
[<ffffffff8212bfe3>] receive_buf drivers/tty/tty_buffer.c:474 [inline]
[<ffffffff8212bfe3>] flush_to_ldisc+0x253/0x370 drivers/tty/tty_buffer.c:533
[<ffffffff8118d131>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
[<ffffffff8118df26>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
[<ffffffff8119d05d>] kthread+0x26d/0x300 kernel/kthread.c:211
[<ffffffff839f8e9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Showing all locks held in the system:
2 locks held by khungtaskd/519:
#0: (rcu_read_lock){......}, at: [<ffffffff813666fc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
#0: (rcu_read_lock){......}, at: [<ffffffff813666fc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
#1: (tasklist_lock){.+.+..}, at: [<ffffffff81425d87>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3772:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211e602>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
2 locks held by syz-executor461/3910:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&tty->atomic_write_lock){+.+.+.}, at: [<ffffffff8210c6f1>] tty_write_lock+0x21/0x60 drivers/tty/tty_io.c:1107
2 locks held by syz-executor461/3911:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&tty->atomic_write_lock){+.+.+.}, at: [<ffffffff8210c6f1>] tty_write_lock+0x21/0x60 drivers/tty/tty_io.c:1107
2 locks held by syz-executor461/3912:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&tty->atomic_write_lock){+.+.+.}, at: [<ffffffff8210c6f1>] tty_write_lock+0x21/0x60 drivers/tty/tty_io.c:1107
2 locks held by syz-executor461/3913:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&tty->atomic_write_lock){+.+.+.}, at: [<ffffffff8210c6f1>] tty_write_lock+0x21/0x60 drivers/tty/tty_io.c:1107
2 locks held by syz-executor461/3914:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&tty->atomic_write_lock){+.+.+.}, at: [<ffffffff8210c6f1>] tty_write_lock+0x21/0x60 drivers/tty/tty_io.c:1107
2 locks held by syz-executor461/3915:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&tty->atomic_write_lock){+.+.+.}, at: [<ffffffff8210c6f1>] tty_write_lock+0x21/0x60 drivers/tty/tty_io.c:1107
2 locks held by syz-executor461/3916:
#0: (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
#1: (&tty->atomic_write_lock){+.+.+.}, at: [<ffffffff8210c6f1>] tty_write_lock+0x21/0x60 drivers/tty/tty_io.c:1107
5 locks held by kworker/u4:4/3920:
#0: ("events_unbound"){.+.+.+}, at: [<ffffffff8118d03e>] work_static include/linux/workqueue.h:186 [inline]
#0: ("events_unbound"){.+.+.+}, at: [<ffffffff8118d03e>] set_work_data kernel/workqueue.c:617 [inline]
#0: ("events_unbound"){.+.+.+}, at: [<ffffffff8118d03e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
#0: ("events_unbound"){.+.+.+}, at: [<ffffffff8118d03e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
#1: ((&buf->work)){+.+...}, at: [<ffffffff8118d078>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
#2: (&tty->ldisc_sem){++++++}, at: [<ffffffff821297b0>] tty_ldisc_ref+0x20/0x80 drivers/tty/tty_ldisc.c:296
#3: (&port->buf.lock/1){+.+...}, at: [<ffffffff8212be16>] flush_to_ldisc+0x86/0x370 drivers/tty/tty_buffer.c:505
#4: (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff8211c6fd>] isig+0xbd/0x4c0 drivers/tty/n_tty.c:1100
=============================================
NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.111-g03c70fe #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
ffff8801d864fd08 ffffffff81eb2729 0000000000000000 0000000000000000
0000000000000000 0000000000000001 ffffffff810b9af0 ffff8801d864fd40
ffffffff81ebda27 0000000000000000 0000000000000000 0000000000000002
Call Trace:
[<ffffffff81eb2729>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81eb2729>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
[<ffffffff81ebda27>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
[<ffffffff81ebd9ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
[<ffffffff810b9bf4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
[<ffffffff81366c94>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
[<ffffffff81366c94>] check_hung_task kernel/hung_task.c:125 [inline]
[<ffffffff81366c94>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
[<ffffffff81366c94>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
[<ffffffff8119d05d>] kthread+0x26d/0x300 kernel/kthread.c:211
[<ffffffff839f8e9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3917 Comm: syz-executor461 Not tainted 4.9.111-g03c70fe #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d6c88000 task.stack: ffff8801b6950000
RIP: 0010:[<ffffffff8135ea30>] c [<ffffffff8135ea30>] check_kcov_mode kernel/kcov.c:66 [inline]
RIP: 0010:[<ffffffff8135ea30>] c [<ffffffff8135ea30>] __sanitizer_cov_trace_pc+0x20/0x50 kernel/kcov.c:100
RSP: 0018:ffff8801b6957970 EFLAGS: 00000246
RAX: ffff8801d6c88000 RBX: ffffc90007cb9000 RCX: 0000000000000003
RDX: 0000000000000000 RSI: ffffffff8211a498 RDI: ffffc90007cba623
RBP: ffff8801b6957970 R08: ffff8801d6c88938 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000869f183c4
R13: 0000000000000007 R14: dffffc0000000000 R15: 0000000869f183c4
FS: 00000000021aa880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004b46a4 CR3: 00000001d7197000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
ffff8801b69579e8c ffffffff8211a498c ffff8801b69579c0c 0000000000000000c
ffffc90007cbb278c ffffed0036147075c ffff8801b0a383acc ffffc90007cb9020c
0000000000002000c ffff8801b0a38000c ffffc90007cbb300c ffffc90007cb9000c
Call Trace:
[<ffffffff8211a498>] __process_echoes+0x5b8/0x780 drivers/tty/n_tty.c:733
[<ffffffff82123ee4>] flush_echoes drivers/tty/n_tty.c:801 [inline]
[<ffffffff82123ee4>] __receive_buf drivers/tty/n_tty.c:1617 [inline]
[<ffffffff82123ee4>] n_tty_receive_buf_common+0xd34/0x2300 drivers/tty/n_tty.c:1711
[<ffffffff82125520>] n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1740
[<ffffffff8211593f>] tiocsti drivers/tty/tty_io.c:2314 [inline]
[<ffffffff8211593f>] tty_ioctl+0xc8f/0x2270 drivers/tty/tty_io.c:2905
[<ffffffff815b2c6c>] vfs_ioctl fs/ioctl.c:43 [inline]
[<ffffffff815b2c6c>] file_ioctl fs/ioctl.c:493 [inline]
[<ffffffff815b2c6c>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
[<ffffffff815b3cef>] SYSC_ioctl fs/ioctl.c:694 [inline]
[<ffffffff815b3cef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
[<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
[<ffffffff839f8cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: c0f c1f c84 c00 c00 c00 c00 c00 c0f c1f c00 c55 c48 c89 ce5 c65 c48 c8b c04 c25 cc0 c7d c01 c00 c65 c8b c15 c2c c93 ccb c7e c81 ce2 c00 c01 c1f c00 c48 c8b c75 c08 c75 c2b c<8b> c90 c80 c12 c00 c00 c83 cfa c02 c75 c20 c48 c8b c88 c88 c12 c00 c00 c8b c80 c84 c